如何传递 python 列表地址

How to pass python list address

本文关键字：地址 列表 python 何传递      更新时间：2023-10-16

我想将 c++ 代码转换为 python。我创建了一个使用 SWIG 的 python 模块来访问 c++ 类。

现在我想将以下 c++ 代码传递给 Python

C++

#define LEVEL 3
  double thre[LEVEL] = { 1.0l, 1.0e+2, 1.0e+5 };
  GradedDouble gd(LEVEL, thre);
  gd.avg(thre);

我需要将上面的代码转换为python

C++用于生成 python 模块的构造函数

GradedDouble::GradedDouble(int n, double *thre)
{
  n_ = n;
  for (int i = 0; i < n_; ++i)
  {
    thre_.push_back(thre[i]);
    grade_.push_back(new grade_type());
  }
}

SWIG 接口文件

/* 文件： 例子.i */

%module example
%include typemaps.i
%apply double * INPUT { double *}
%apply double * INPUT { double *buf };
%{
#include "Item.h"
#include "GradedComplex.h"
#include "GradedDouble.h"
void avg(double *buf);
%}
%include <std_string.i>
%include <std_complex.i>
%include "Item.h"
%include "GradedComplex.h"
%include "GradedDouble.h"
%template(Int) Item<int>;
%template(Double) Item<double>;
%template(Complex) Item<std::complex<double> >;

示例 python 模块函数 

class GradedDouble(_object):
    __swig_setmethods__ = {}
    __setattr__ = lambda self, name, value: _swig_setattr(self, GradedDouble, name, value)
    __swig_getmethods__ = {}
    __getattr__ = lambda self, name: _swig_getattr(self, GradedDouble, name)
    __repr__ = _swig_repr
    def __init__(self, *args): 
        this = _example.new_GradedDouble(*args)
        try: self.this.append(this)
        except: self.this = this
    __swig_destroy__ = _example.delete_GradedDouble
    __del__ = lambda self : None;
    def push(self, *args): return _example.GradedDouble_push(self, *args)
    def avg(self, *args): return _example.GradedDouble_avg(self, *args)
GradedDouble_swigregister = _example.GradedDouble_swigregister
GradedDouble_swigregister(GradedDouble)

如何转换它？

在SWIG中使用原始双*和长度作为接口更加困难。 您需要为参数对编写一个类型图，该类型图可以智能地读取给定大小的数组。 更易于使用SWIG的内置矢量支持。

示例，具有显示支持：

GradedDouble.i

%module GradedDouble
%{
#include "GradedDouble.h"
%}
%include <std_vector.i>
%include <std_string.i>
%template(DoubleVector) std::vector<double>;
%rename(__repr__) ToString;
%include "GradedDouble.h"

GradedDouble.h

#include <vector>
#include <string>
#include <sstream>
class GradedDouble
{
    std::vector<double> thre_;
public:
    GradedDouble(const std::vector<double>& dbls) : thre_(dbls) {}
    ~GradedDouble() {}
    std::string ToString() const
    {
        std::ostringstream ss;
        ss << "GradedDouble(";
        for(auto d : thre_)
            ss << ' ' << d;
        ss << " )";
        return ss.str();
    }
};

输出

>>> import GradedDouble as gd
>>> x=gd.GradedDouble([1.2,3.4,5.6])
>>> x
GradedDouble( 1.2 3.4 5.6 )

执行此操作的另一种方法是使用 SWIG cpointer 和 carray。示例代码如下：

接口文件：

%module example
%include "cpointer.i"
%{
#include "Item.h"
#include "GradedDouble.h"
extern void avg(double *buf);
%}
%pointer_class(double, doublep);
%include "carrays.i"
%array_class(double, doubleArray);
%include <std_string.i>
%include "Item.h"
%include "GradedDouble.h"
%template(Double) Item<double>;

蟒蛇代码：

LEVEL = 3
thre = [1, 100, 10000]
a = example.doubleArray(LEVEL)
for i in xrange(LEVEL):
    a[i] = thre[i]
gd=example.GradedDouble(LEVEL,a)
result = example.doublep()
gd.avg(result)
print result.value()

这对我有用

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